Will Vidalia onions keep longer if I store them in the basement ( storm shelter)
Possible but they really aren't a storage onion variety. Too much sugar. However they dice and freeze or dehydrate exceptionally well.
For freezing just chop and place measured amounts like 1 cup in freezer bags, remove as much air as possible, press flat, and place bags in freezer. To dehydrate, chop spread in a thin layer on dehydrator sheet and dry till crispy. Store indefinitely in glass jars.
20 years ago, Vidalias were available only very soon after harvesting. At that time, the Vidalia growers recommended tieing the onions in panty hose with a knot between each bulb. The hose were then hung in the basement. Since they did not touch there was much less loss.
However a few years back U of Ga and Ga Dept of Ag did a lot of research and Vidalias are now held under carefully controlled temperature and moisture ... and are available for a much longer period.
Although I'm a native Georgian and love Vidalias, I prefer to follow the "Sweet Onion Trail." I can't recall all the names now, but the first sweets are imported from Central America ... then come the Texas (1040, I think). The Vidalias are followed by sweets from the Pacific Northwest.
As Dave noted, they do keep wonderfully frozen -- but the texture does change when frozen.
-another option -- is to chop, saute and then put whatever amount you want into freezer bags.
I find this a timesaver in cooking. I like to use sauteed onions in meatloaf, pasta sauces, etc.